Absence of antiviral activity in recombinant B cell stimulatory factor 2 (BSF-2).

Recombinant B cell stimulatory factor 2 (rBSF-2) did not display any detectable level of antiviral activity when using human diploid fibroblasts, DIP-2, FS-4, FS-7, amnion-derived WISH and FL cells with vesicular stomatitis virus (VSV) and Sindbis virus as challenging agents (less than 2.5 X 10(2) IU/mg). Furthermore anti-IFN-beta could not neutralize the immunoglobulin-inducing activity of BSF-2. Moreover anti-BSF-2 could not neutralize the antiviral activity of IFN-beta. The data indicate that BSF-2 is functionally and immunologically not related to IFNs.